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I was using coredns inside VNET jails for a long time, but since one day I have a strange problem. After restart of coredns service sometimes I have no access to the coredns server by UDP (TCP always works correctly). There is no problem to bind the port (netstat shows it as 'LISTEN' inside the jail), but if I try to request something - there is no answer. Restart of the service can fix the problem, or the problem can stay here. After some restarts everything starts to work correctly.
I don't see this problem if I start coredns directly on the host, out of jail.
For information - VNET in a kernel mechanism that permits to have completely separated network stack inside jail containers.
I tried to communicate using UDP with netcat listening inside the same jail - there is no problem, so this is not a problem of network stack. Maybe there is something like race conditions during coredns initialization.
How can I debug/resolve this problem at coredns level? I'm capable to rebuild coredns binary with any patch to test...
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Hello,
I was using coredns inside VNET jails for a long time, but since one day I have a strange problem. After restart of coredns service sometimes I have no access to the coredns server by UDP (TCP always works correctly). There is no problem to bind the port (netstat shows it as 'LISTEN' inside the jail), but if I try to request something - there is no answer. Restart of the service can fix the problem, or the problem can stay here. After some restarts everything starts to work correctly.
I don't see this problem if I start coredns directly on the host, out of jail.
For information - VNET in a kernel mechanism that permits to have completely separated network stack inside jail containers.
I tried to communicate using UDP with netcat listening inside the same jail - there is no problem, so this is not a problem of network stack. Maybe there is something like race conditions during coredns initialization.
How can I debug/resolve this problem at coredns level? I'm capable to rebuild coredns binary with any patch to test...
Peter
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